Re: [RFC] vfs: cleanup of permission()

[Sam Vilain <sam@vilain.net>]

Trond Myklebust wrote:
>>the second part is actually a hack to help nfs and fuse
>>to get the 'required' information until there is a proper
>>interface (at the vfs not inode level) to pass relevant
>>information (probably dentry/vfsmount/flags)
> The nameidata _IS_ the vfs structure for storing path context
> information. You seem to be suggesting we need yet another one. Why?

Because you can't make a nameidata without a lookup, and file based 
operations don't do a lookup.  However you still have the vfsmnt and 
inode hanging off the file struct.

Either that or we make a dummy nameidata structure for this situation, 
possibly a filehandle relative lookup as used by openat() et al.

>>>Secondly, an intent is _not_ a permissions mask by any stretch of the
>>>imagination.
>>see above
>>>IOW: at the very least make that intent flag a separate parameter.
>>IMHO it would be good to remove them completely form the
>>current permission() checks.
> Vetoed!
> Redundant RPC calls have performance costs to the client, the server and
> the network. That intent information is there in order to allow the
> filesystem to figure out whether or not it needs to do the permissions
> check, or if that check is already being done by other operations.
> Removing the intents are therefore not an option.

OK, so we either make it an extra parameter or 'properly' stack them 
into a single word.  Do you have any preferences either way there?

Sam.